1. Field of the Invention
The present invention relates to a vehicular air conditioning apparatus mounted in a vehicle for blowing air into a vehicle compartment that has been adjusted in temperature by a heat exchanger, for thereby adjusting temperature of the vehicle compartment.
2. Description of the Related Art
In a vehicular air conditioning apparatus that is mounted in a vehicle, internal and external air is introduced into a casing by a blower, and after cooled air, which has been cooled by an evaporator (heat exchanger) that forms a cooling means, and heated air, which has been heated by a heater core (heat exchanger) that forms a heating means, are mixed together in the casing at a predetermined mixing ratio, the mixed air is blown out from a defroster blow-out port, a face blow-out port, or a foot blow-out port, whereby adjustment of temperature and humidity in the vehicle compartment is carried out.
Generally, in the vehicular air conditioning apparatus as mentioned above, for example, as disclosed in Japanese Laid-Open Patent Publication No. 2003-220820, a defroster blow-out port is disposed in the vicinity of a front window of a vehicle, i.e., on a forward side of the vehicle. Fog on the front window is eliminated by blowing air from the defroster blow-out port. On the other hand, a vent blow-out port is disposed on a rearward side of the vehicle with respect to the defroster blow-out port, for cooling air in the vicinity of the faces of passengers by blowing air from the vent blow-out port.
In the aforementioned vehicular air conditioning apparatus, in a bi-level mode, where air is blown in the vicinity of the faces and feet of passengers in the vehicle compartment, it is ideal that a large temperature difference is secured between the temperature of air supplied from the vent blow-out port opposing the faces of passengers and the temperature of air supplied to the vicinity of the feet of passengers. It is, however, difficult to secure a large temperature difference between the temperature of air blown in the vicinity of the faces of passengers and the temperature of air blown in the vicinity of the feet of passengers in the vehicle compartment, due to layout of passages in a casing of an air conditioning apparatus and layout of switching doors for switching a flow state of the air.
Further, in a heat-defroster mode, in which in the vehicle compartment, air is blown both in the vicinity of the feet of passengers and in the vicinity of a front window for eliminating fog on the front window from a defroster blow-out port, it is desired to equalize a temperature of air blown in the vicinity of the feet of passengers with a temperature of air blown in the vicinity of the front window. The air heated by a heating means (heat exchanger) relatively tends to flow into a passage that blows the air in the vicinity of the feet of passengers. On the other hand, the air cooled by a cooling means (heat exchanger) without passing the heating means tends to flow into the defroster blow-out port. Therefore, air is blown in the vicinity of the feet of passengers and the front window, while insufficiently mixing the air heated by the heating means and the air cooled by the cooling means. As a result, an undesirable temperature difference occurs between a temperature of the air blown in the vicinity of the feet of passengers and a temperature of the air blown in the vicinity of the front window. Then, for example, fog on the front window cannot be eliminated satisfactorily.